Quantum coherent control of two-photon transitions by square phase-modulation

A femtosecond laser pulse can be tailored to control the two-photontransitions using the ultra-fast pulse-shaping technique. This papertheoretically and experimentally demonstrates that two-photontransitions in molecular system with broad absorption line can beeffectively controlled by square phase-modulation in frequencydomain, and the influence of all parameters characterizing thesquare phase-modulation on two-photon transitions is systemicallyinvestigated and discussed. The obtained results have potentialapplication in nonlinear spectroscopy and molecular physics.